Theodo (about 625 – 11 December c. 716), also known as Theodo V and Theodo II, was the Duke of Bavaria from 670 or, more probably, 680 to his death. It is with Theodo that the well-sourced history of Bavaria begins. He strengthened his duchy internally and externally and, according to the medieval chronicler Arbeo of Freising, he was a prince of great power whose fame extended beyond his borders.